Pipe Hacksawing Guide Clamp

I needed to cut some 25mm pipe with a hacksaw, because I'm making an [MPCNC](http://www.vicious1.com/). But I couldn't get the cut straight, and the saw kept skipping.

So I designed this little guide clamp device: you put two guides surrounding where you want to cut, with two protective shims between, and the saw can only go along the line of the guides. The guides are tightened with an M4 bolt.

The shims ensure a sawblade-width gap; they are intended to be cheap and sacrificial, preventin